[grpc_http2]: https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md
 [https_server_sample]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/HttpsServer.java
 [jetty_8_252]: https://webtide.com/jetty-alpn-java-8u252/
 [junit_5_rules]: https://junit.org/junit5/docs/current/user-guide/#migrating-from-junit4-rulesupport

                    if (maxDate && calendar[row][col].isAfter(maxDate, 'day'))
                        classes.push('off', 'disabled');

                    //don't allow selection of date if a custom function decides it's invalid
                    if (this.isInvalidDate(calendar[row][col]))
                        classes.push('off', 'disabled');

                    //highlight the currently selected start date